Dual-mode fluorimetric and colorimetric sensors based on iron and nitrogen co-doped carbon dots for the detection of dopamine

•Blue emissive Fe, N co-doped carbon dots with QY of 23.89% were fabricated.•Dual-mode fluorimetric/colorimetric detection for DA was achieved with LOD of 0.29 μM and 2.31 μM.•AFC-CDs can fulfill the detection in real water and food samples successfully.•The detection mechanism based on proposed electron transfer was deduced. Determination of dopamine (DA) is crucial for its intimate relationship with clinical trials and biological environment. Herein, Fe, N co-doped carbon dots (AFC-CDs) were fabricated by optimizing precursors and reaction conditions for fluorimetric/colorimetric dual-mode sensing of DA. With synergistic influence of Förster resonance energy transfer and static quenching effect, DA significantly quenched the blue luminescence of AFC-CDs at 442 nm, the production of recognizable tan-brown complex caused evident colorimetric response, achieved the dual-mode fluorimetric/colorimetric sensing for DA. The excellent selectivity and satisfied sensitivity can be confirmed with the limit of detection at 0.29 μM and 2.31 μM via fluorimetric/colorimetric mode respectively. The reliability and practicability were proved by recovery of 94.81–101.61% in real samples. Notably, the proposed electron transfer way between AFC-CDs and DA was hypothesized logically, indicated dual-mode probe provided a promising platform for the sensing of trace DA, and could be expanded in environment and food safety.